EP0023951B1 - Motor driven hand tool, especially combination tool for home-workers - Google Patents

Description

State of the art

The invention relates to a motor-driven hand tool, in particular a do-it-yourself combination machine, according to the preamble of the main claim. While the right-hand rotation of the work spindle is the normal and common direction of rotation of the hand tool, the left-hand rotation of the work spindle is mainly used in connection with screws attached to the hand tool, mostly here for unscrewing screws, but sometimes also for screwing in left-handed screws. In a known drilling machine with clockwise and anticlockwise rotation, there is the possibility of attaching attachments or additional devices, such as saws, milling or the like, to the clamping neck of the drilling machine, so that this drilling machine can be used for other purposes. It is possible to drive the work spindle with counterclockwise rotation when the attachment is installed. A rotation of the attachments, such as circular saws or milling, in the left-hand rotation not only leads to destruction of the attachment, but also to a considerable risk to the user of the hand tool. Known drilling machines of this type are sometimes also equipped with an additional device, such as an impact boring machine or the like. If the work spindle is drilled with the hammer drill and counterclockwise, this will inevitably lead to the destruction of the hard metal drill.

Advantages of the invention

The motor-driven hand tool according to the invention, in particular a do-it-yourself combination machine, with the characterizing features of the main claim has the advantage that damage to tools driven with the hand tool, such as drills, milling machines, saws or the like, and also a risk to the user of the hand tool is prevented by the intentional or inadvertently switched on counterclockwise rotation of the work spindle. When the impact boring machine is engaged and / or when attachments are attached which are not suitable for counterclockwise rotation, the user is automatically deprived of the possibility of switching on the counterclockwise rotation of the work spindle on the hand tool. Conversely, the user is initially forced to switch on the clockwise rotation for the work spindle if he wants to engage the hammer drill and / or attach attachments to the hand tool that are not designed for counterclockwise rotation. The hand tool according to the invention also has the further advantage that the locking device according to the invention for counterclockwise rotation does not require any change in the structure of the hand tool and can be achieved with relatively few means. Both the engine structure and the conventional transmission structure known per se with its construction elements, such as safety clutch, gear shift transmission or the like, can be retained unchanged.

The measures listed in the subclaims permit advantageous further developments and improvements to the hand tool specified in the main claim. The embodiments of the invention according to claims 5 to 13 are particularly advantageous, each of which, individually or in combination, enables the locking device according to the invention to be implemented in a structurally simple and inexpensive manner.

drawing

• Fig. 1 eine Seitenansicht einer Heimwerker-Kombinationsmaschine, ausschnittweise und teilweise geschnitten,
• Fig. 2 einen Schnitt längs der Linie II-II in Fig. 1,
• Fig. 3 einen Schnitt längs der Linie 111-111 in Fig. 1, ausschnittweise,
• Fig. 4 eine Draufsicht eines Spannhalses der Kombinationsmaschine in Richtung Pfeil IV in Fig. 1, ausschnittweise,
• Fig. 5 einen Schnitt längs der Linie V-V in Fig. 4,
• Fig. 6 eine Draufsicht auf den Spannhals der Kombinationsmaschine gemäss einem zweiten Ausführungsbeispiel,
• Fig. 7 einen Schnitt längs der Linie VII-VII in Fig. 6.

Embodiments of the invention are shown in the drawing and explained in more detail in the following description. Show:

• 1 is a side view of a home improvement combination machine, partially and partially cut,
• 2 shows a section along the line II-II in FIG. 1,
• 3 shows a section along the line 111-111 in FIG. 1, in sections,
• 4 is a plan view of a neck of the combination machine in the direction of arrow IV in FIG. 1, in sections,
• 5 shows a section along the line VV in FIG. 4,
• 6 is a plan view of the clamping neck of the combination machine according to a second embodiment,
• 7 shows a section along the line VII-VII in FIG. 6.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS The home improvement combination machine shown in FIGS. 1 to 5 as an example of an electric motor-driven hand tool has a housing 10 and a work spindle 11 mounted in the housing 10. The work spindle 11 is driven by an electric motor, not shown, via a gear transmission 12. Here, the work spindle 11 can be driven both in the left and in the right direction. In a known manner, the gear transmission 12 has a countershaft 13, which is usually driven by the electric motor via a safety clutch. Depending on the number of gear speeds provided, there are gears 14 on the work spindle 11, which can optionally be rotatably coupled to the work spindle 11 by means of a pull wedge 19.

In the present exemplary embodiment, two gear speeds of the work spindle 11 in clockwise rotation (designated by “1” and “2” in FIG. 1) and one gear speed of the work spindle 11 in clockwise rotation (identified by “L” in FIG. 1) are provided. Accordingly, two gear wheels 14 are seated on the work spindle 11, of which the gear wheel 15 can be seen in FIG. 2. The gearwheel 15 drives the work spindle 11 in a non-rotatable connection and rotates counterclockwise via a turning wheel 16 with the countershaft 13 in

Intervention. The two other gears 14 mesh directly with the countershaft 13 and, when they are connected in a rotationally fixed manner to the work spindle 11, drive them in clockwise rotation at two different speeds.

To switch the gearbox, a direction of rotation switchover device 17 (FIGS. 1 and 2) acts on the gearbox gearbox 12, which in the exemplary embodiment also serves to switch the number of gears in clockwise rotation of the work spindle 11. This direction of rotation changeover device 17 has a changeover switch 18 which has at least one switch position for clockwise rotation, here two switch positions for clockwise rotation «1» «2» and a switch position for counterclockwise rotation «L». The switch 18 can be transferred manually into its switching positions. For this purpose, the changeover switch 18 is pivotally mounted in the housing 10 and is provided with a toothed segment 20, which is designed here as a full toothed ring, which meshes in an axially displaceable toothed rack 21. The toothed rack 21 carries a shift finger 22 which engages the pull wedge 19 and axially shifts it according to the position of the changeover switch 18, so that the respective gear wheel 14 is connected to the work spindle 11 in a rotationally fixed manner via the pull wedge 19.

The combination machine has a hammer drill 23 which is known per se and which can be seen in detail in FIG. 1. To engage and disengage the percussion boring machine 23, an adjusting bolt 24 is provided, which is designed as a pivot and has an engagement and disengagement position for the percussion boring machine 23 which are circumferentially offset by approximately 180 °. In Fig. 1, the adjusting bolt 24 is shown in its hammer drill disengaging position. In this position, the hammer drill 23 is blocked by the ball 25.

The housing 10 of the combination machine has an annular clamping neck 26 at the outlet opening of the work spindle 11 from the housing 10, the jacket of which forms a receiving surface 27 for holding attachments or additional devices such as a saw, milling machine or the like. With a circular saw, e.g. the saw blade is non-rotatably connected to the work spindle 11, but the holder for the guide frame is pushed onto the clamping neck 26 and clamped there. The holder of the guide frame is essentially adapted to the shape of the clamping neck 26.

To prevent the counter-clockwise rotation of the work spindle 11 when the impact boring machine 23 is engaged and / or when the attachment is held on the clamping neck 26, the combination machine has a locking device 28 which is coupled to the changeover switch 18. Part of this locking device 28 is a locking member 29, which engages with the hammer drill 23 in such a way that when the switch 18 is in its counterclockwise switching position “L”, the hammer drill 23 is engaged and, conversely, when the hammer drill 23 is engaged, the switch 18 is transferred into its counterclockwise switching position «L» is blocked (Fig. 1 and 3). The locking device 28 also has a further locking member 30 (FIGS. 4 and 5) which is arranged on or in the immediate vicinity of the receiving surface 27 on the clamping neck 26 in such a way that when the switch 18 is in its counterclockwise switching position “L”, it is pushed open of an attachment on the receiving surface 27 on the clamping neck 26 and vice versa when the attachment is placed on the clamping neck 26, the transfer of the changeover switch 18 into its counterclockwise switching position “L” is blocked. Depending on whether the electric hand tool is a combination machine without a hammer drill 23 or only a hammer drill without the possibility of attaching attachments, one of the two locking members 29, 30 can of course be missing.

The two locking members 29 and 30 each have two blocking positions. The locking member 29 is arranged and designed in such a way that it can be moved into the one blocking position by actuating the switch 18 and into the other blocking position by engaging the hammer drill 23 and blocks its opposite actuation in the respective blocking position, i.e. If the blocking member 29 has been transferred to the one blocking position via the changeover switch 18, then in this blocking position it is blocked against actuation which is necessary for engaging the hammer drill 23. In the same way, the locking member 30 is arranged and designed in such a way that it can be transferred into the one blocking position by actuating the switch 18 and into the other blocking position by pushing on attachments onto the clamping neck 26 and also blocks its opposite actuation in the respective blocking position.

As shown in broken lines in FIG. 1, the locking device 28 has a plunger 31, which is connected to the changeover switch 18 via the rack 21 and engages with the locking member 29. The plunger 31 has a locking member actuating surface 32 which is arranged at an angle to the plunger axis and is designed here as a truncated cone. In addition, the plunger 31 also has a latching surface 33, behind which the locking member 29 can engage (FIGS. 1 and 3). This latching surface 33 is designed here as an annular stop shoulder 34 projecting transversely on the plunger 31 and delimiting the locking member actuating surface 32 on the end face. The locking member 29 is formed here as a locking pin 35 axially displaceable transversely to the plunger 31. As can be seen in FIG. 3, the locking pin 35 is arranged in a stepped bore 36 in the interior of the housing 10 and assumes a basic position under the influence of two resilient resetting elements which act on it in opposite directions and are designed here as cylindrical helical springs 37 and 38 . The helical spring 37 is supported on the one hand on the locking pin 35, namely on a centrally arranged annular flange 39, and on the other hand on the stepped shoulder of the stepped bore 36. The coil spring 38 also engages the ring flange 39 of the locking pin 35 and is supported on the other hand on a closure sleeve 40, which is inserted into the stepped bore 36 on the end face and held there and guides the locking pin 35. The locking pin 35 enables a mutual coupling of the ram 31 and the adjusting bolt 24 of the hammer drill 23.

The adjusting bolt 24 has a locking groove 41 (FIG. 1) which faces the locking pin 35 only in the engaged position of the adjusting bolt 24 shown in FIG. 1. In the adjustment direction of the adjusting bolt 24, a recess 42 adjoins the recess groove 41, which continuously transfers from the recess groove 41 to the outer surface 42 of the adjusting bolt 24 and forms a locking pin actuating surface 43. In the basic position of the locking pin 35 shown in FIG. 3, it lies with its one end face directly in front of the recess groove 41 without dipping into it, the end face protruding beyond the outer contours of the adjusting bolt 24 into the recess 42. The other end of the locking pin 35 is at a distance corresponding to the height of the stop shoulder 34 from the plunger 31 (FIG. 1). However, the locking pin 35 can only assume this basic position if the adjusting bolt 24 has assumed its hammer drilling mechanism disengagement shown in FIG. 1 and the changeover switch 18 is in its clockwise switching position, be it - as shown in FIG. Shift position "1 _" or gear shift position "2".

If the changeover switch 18 in FIG. 1 is pivoted counterclockwise and transferred to its counterclockwise switching position “L”, the toothed rack 20 is shifted to the left in FIG. 1 via the toothed segment 20. As a result, the locking member actuating surface 32 of the plunger 31 slides along the abutting end face of the locking pin 35 and pushes the locking pin 35 into the recess groove 42 of the adjusting bolt 24 by compressing the coil spring 37. The changeover switch 18 remains in its counterclockwise switching position “L”, so the front end of the locking pin 35 remains in the recess groove 42 and the adjusting bolt 24 is blocked. The hammer boring machine 23 is thus locked in its inactive position and cannot be engaged. This is only possible after the changeover switch 18 has been returned to one of its clockwise switching positions “1 or“ 2 ”, so that the plunger 31 shifts to the right again and the locking member actuating surface 32 releases the locking pin 35 so that it is underneath assumes the restoring action of the helical spring 37 shown in FIG. 3.

If, in this basic position of the locking pin 35, the adjusting bolt 24 is rotated counterclockwise in FIG. 1 in order to engage the hammer drill 23, the locking pin actuating surface 43 of the recess 42 displaces the locking pin 35 against the restoring force of the helical spring 38. Finally, the end face of the Lock pin 35 on the outer surface 44 of the adjusting bolt 24. In the above-described displacement of the locking pin 35, its other end is brought closer to the plunger 31 and engages behind the stop shoulder 34 of the plunger 31. This limits the axial displacement of the plunger 31. The push-button 31 can only be shifted to the right in FIG. 1, which enables the combination machine to be switched on in the second right-hand rotation by means of the changeover switch 18. A pivoting of the switch 18 into its counter-clockwise switching position “L” is reliably prevented, since a displacement of the toothed rack 21 and thus of the plunger 31 from the position shown in FIG. 1 to the left is blocked by the stop shoulder 34 resting against the locking pin 35. When the impact boring machine 23 is engaged, the counterclockwise rotation of the combination machine cannot be switched on. This is in turn only possible after the adjustment bolt 24 has been transferred back to its hammer drill disengagement position, in which the recess 42 and the locking groove 41 in the adjustment bolt 24 enable the locking pin 35 to be reset to its basic position.

The locking device 28 has a further plunger 45 which, like the other plunger 31, is rigidly connected to the toothed rack 21 (FIGS. 1 and 5). This plunger 45 extends with a plunger section 45 up to the receiving surface 27 arranged on the clamping neck 26 for attachments. Provided in the clamping neck 26 is a bore 47 aligned parallel to the work spindle 11, into which the plunger section 46 is immersed (FIG. 5). Furthermore, a cage opening 48, which is arranged transversely to the bore 47, is provided in the clamping neck 26, in which a locking body, here a locking ball 49, is held with radial play, which forms the locking member 30 already mentioned at the beginning. In the one blocking position of the locking member 30, the locking ball 49 dips into the bore 47, and in the other locking position of the locking member 30, the locking ball 49 partially emerges from the cage opening 48 and protrudes above the receiving surface 27. In the last-mentioned blocking position, an attachment cannot be pushed onto the receiving surface 27 of the clamping neck 26, since it abuts the protruding locking ball 49 and therefore cannot be pushed onto the clamping neck 26. The plunger 45, like the plunger 31, also has a locking member actuating surface 50 and a latching surface 51, both of which are formed by the wedge-like front end of the plunger.

If the changeover switch 18 is pivoted into its counter-clockwise switching position “L”, the rack 21, as mentioned, shifts to the left in FIG. 1. The plunger 45 thus pushes further with its plunger section 46 into the bore 47 in the clamping neck 26. When it is advanced, the plunger 45 displaces the locking ball 49 completely from the bore 47. In the counterclockwise switching position “L _{” of} the switch 18, the plunger section 46 lies behind the locking ball 49 and prevents the locking ball 49 from being pushed back Locking ball 49 protrudes on the receiving surface 27 and prevents the attachment of a front attachment.

If the changeover switch 18 is in the position shown in FIG. 1, it is possible to slide an attachment onto the clamping neck 26, since the plunger 45 assumes the position shown in FIG. 5 and the locking ball 49 when the attachment is pushed into the hole 47 can be inserted so that it no longer protrudes on the receiving surface 27. If the attachment is now clamped on the clamping neck 26, the changeover switch 18 can no longer be pivoted into its counterclockwise switching position “L”, since in this case the tappet 45 pushes against the locking ball 49 with its wedge-like end. Since the locking ball 49 is blocked by the attachment in the position shown in FIG. 5, a further displacement of the plunger 45 and thus a pivoting of the changeover switch 18 in the direction of its counterclockwise switching position “L” is prevented.

In the combination machine according to the exemplary embodiment in FIGS. 6 and 7, a plunger 52 connected in the same way to the toothed rack 21 extends with a plunger section 53 to the receiving surface 27 on the clamping neck 26. In this exemplary embodiment, the plunger 52 also forms the same at the first embodiment of the combination machine separately provided locking member. A passage opening 54 is provided in the housing 10 outside the clamping neck 26, through which the tappet 52 with its tappet section 53 projects parallel to the work spindle 11 and the receiving surface 27 and can move tangentially on the receiving surface 27. In one blocking position of the plunger 52, the plunger end 55 extends close to the receiving surface 27 (FIG. 7), while in the other blocking position the plunger section 53 at least partially overlaps the receiving surface 27. An axially extending guide groove 56 is provided on the clamping neck 26 for guiding the front plunger section 53.

The operation of this variant of the locking device 28 is essentially the same as described above for FIGS. 4 and 5. If the changeover switch 18 is in its counter-clockwise switching position “L”, the plunger section 53 is pushed so far onto the receiving surface 27 that an attachment cannot be pushed onto it. If, on the other hand, an attachment is already clamped on the receiving surface 27, the plunger end 55 of the plunger 52 lies directly in front of the holder of the attachment which engages on the receiving surface 27 and is prevented from moving to the left in FIG. 7. As a result, the changeover switch 18 cannot be pivoted from its position shown in FIG. 1 into its counterclockwise switching position “L”.

Claims (14)

1. A motor driven hand tool, particularly a domestic combination machine, comprising a working spindle (11) mounted on the housing (10), a gear drive (12) driving the working spindle (11) clockwise and anti-clockwise and a device for changing the sense of rotation acting on the gear drive (12) and which has a change-over switch (18) which can be moved into at least one clockwise and one anti-clockwise switching position, characterised by a locking device (28) which is coupled to the change-over switch (18) and has at least one locking member (29, 30) which is in engagement with an additional device if necessary provided in the hand tool, such as a percussion drilling mechanism (23) or the like and/or is arranged in the immediate vicinity of a surface (27) serving to form the mounting for adaptors, in such a manner that, on positioning the change-over switch (18) in its anti-clockwise operating switching position (L) the switching-in of the additional device (23) and/or the mounting of an adaptor on the receiving surface (27) and with the additional device (23) switched in and/or a mounted adaptor, movement of the change-over switch (18) into its anti-clockwise switching position (L) is blocked.

2. A hand tool according to claim 1, characterised in that the locking member (29, 30) has two locking positions and is arranged and designed so that it can be moved into one blocking position by actuating the change-over switch (18) and into the other blocking position by switching-in the additional device (23) and/or by mounting the adaptor and in the respective blocking position it blocks its actuation in the opposite sense.

3. A hand tool according to claim 1 or 2, characterised in that the locking device (28) has at least one push rod (31, 45; 53) operably connected to the change-over switch (18) and which is in engagement with the locking member (29, 30) and has a locking member actuating surface (32, 50) and a latching surface (33, 51) behind which the locking member (29, 30) can drop, limiting the push rod movement.

4. A hand tool according to claim 3, characterised in that the push rod (31, 45) has an axially displaceably guided rack (21) and that the change-over switch (18) is arranged for pivotal movement and has a toothed segment (20) meshing with the rack (21).

5. A hand tool according to claim 3 or 4, characterised in that the locking member actuating surface (32) is arranged at an inclination to the push rod axis, preferably made bevelled, and that the latching surface (33) is preferably formed as an annular abutment shoulder (34) extending transversely on the push rod (31), preferably bounding the locking member actuating surface (32) at the end, and the locking member (29) is formed as an axially displaceable locking pin (35) preferably aligned transversely with respect to the push rod (31).

6. A hand tool according to claim 5, characterised in that an adjustable pin (24) is provided for switching the percussion drilling mechanism (25) in and out and has a locking groove (41) which faces the locking pin (35) only in its switched-out position and has at least one depression (42) provided with a locking pin actuating surface (43) adjoining the locking groove (41) in the adjustment direction of the adjusting pin (24) continually changing from the latter to the outer surface (44) of the adjusting pin (24), that with the adjusting pin (24) in the switched-out position and with the change-over switch (18) in the clockwise switching position, the locking pin (35) takes up a basic position in which one of its ends lies in the region of the depression (42) without entering the locking groove (41) and its other end is at a distance from the push rod (31) corresponding substantially to the level of the abutment shoulder and that the locking pin (35) is arranged for displacement out of its basic position in both directions against a return force.

7. A hand tool according to claim 6, characterised in that two resilient return members each acting in displacement directions opposite to one another and which are preferably formed as cylindrical helical springs (37, 38) engage the locking pin (35).

8. A hand tool according to claim 7, characterised in that the locking pin (35) is arranged in a stepped housing bore and is guided in a closure sleeve (40) closing the stepped bore (36) and that a respective one of the helical springs abuts against the stepped shoulder of the stepped bore (36) and one against the closure sleeve (40).

9. A hand tool according to one of claims 6 to 8, characterised in that the adjusting pin (24) is formed as a rotary pin and the in and out positions for the percussion drilling mechanism (23) are displaced from one another by substantially 180 degrees.

10. A hand tool according to claim 3, characterised in that the push rod (45, 52) is displaceably guided in the housing (10) and has a push rod section (46, 53) which extends up to the receiving surface (27) arranged on a housing clamping neck (26).

11. A hand tool according to claim 10, characterised in that the clamping neck (26) has a bore (47) aligned parallel to the working spindle (11) and into which the push rod section (46) penetrates, and a cage opening (48), arranged transversely with respect to the bore (47) and in which is retained, with radial clearance, a locking element forming the locking member (30), particularly a locking ball (49) which, in one blocking position of the locking member (30), limiting the movement of the push rod, penetrates into the bore (47) and in the other blocking position of the locking member (30) partially protrudes out of the cage opening (48), projecting beyond the receiving surface (27).

12. A hand tool according to claim 11, characterised in that the locking member actuating surface (50) and the latching surface (51) are formed by the substantially wedge-shaped end of the push rod (45).

13. A hand tool according to claim 10, characterised in that locking member and push rod (52) are integral and that an opening (54) is provided in the housing (10), outside the clamping neck, through which the push rod section (53) projects parallel to the working spindle (11), preferably tangentially to the receiving surface (27) and that, in one blocking position, the push rod section (53) extends into the vicinity of the receiving surface (27) and in the other blocking position, at least partially overlaps the receiving surface (27). 14. A hand tool according to claim 13, characterised in that an axially extending guide groove (56) in which the push rod section (53) is at least partially guided, is provided in the receiving surface (27).

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